Air mixer for unit heaters



N0V- 3, 1942 A R. c. JEERTINGER 2,300,574

AIR MIXER FOR UNIT HEATERS Filed Nov. 9, 1938 4 sheets-sheet 1 w N WWW 1% Nov. 3, 1942. R. c. JEPERTlNGr-:R

AIR MIXER FOR UNIT HEATERS 4 SheetsfShee't 2 Filed Nov. 9, 1958 [7a2/@Rf f N0V- 3, 1942 R. c. JEPERTINGER 2,300,574

AIR MIXER FOR UNIT HEATERS Filed Nov. 9, 1938 4 sheets-sheet 3 NCW- 3, l942- R. c. .JEPl-:RTINGER 2,300,574 l AIR MIXER FOR UNIT HEATERS Filed Nov. 9, 1938 4 Sheets-Sheet 4 Patented Nov. 3, 1942 2,300,574 Am MIXER Fon UNIT nEA'rEns Richard C. Jepertinger, Milwaukee, Wis., assignor to Modine Manufact Wis., a corporation of Application November 9, 1938, Serial No. 239,687

24 Claims.

This invention relates to unit heater construction, and particularly to the manner of directing the air therefrom, and controlling the condition of the air discharged thereby.

One object of the present invention is to provide a novel construction and arrangement whereby heated air before being discharged from the unit is properly mixed with air of room temperature in a manner to readily co-mingle with the air of the space to be heated.

Another object of the invention is to provide novel means for co-mingling air of different temperatures to form a proper mixture, and prevent stratifying of the air due to excessive temperature differentials.

Another object of the invention is to provide a novel construction and arrangement in a unit heater whereby a maximum quantity of air may be circulated with a minimum amount of horse power, and wherein a device of more 'highly condensed heating surface may be used, while providing a lower discharge-air temperature found to be most desirable in unit heater work.

Another object of the invention is to provide means whereby room-temperature, Venturi or secondary air may be air stream of the unit heater, thereby lowering the temperature of the entire amount of air handled. and conditioning the air stream for suitable mixing with the air of the room to be heated.

' Another object of the invention is to provide a novel construction and arrangement of ad-V justable deilectors for directing the primary air stream into the space to be heated, and having means associ-ated therewith for introducing Venturi or secondary air into the air stream as the latter is discharged from the unit.

Another object of the invention is to provide novel means for retaining the defiectors in various positions of adjustment.

Another object of the invention is to provide novel means whereby the quantity or volume of secondary air admitted to the air stream may be readily varied.

A further object of the invention is to provide a novel construction and arrangement whereby the secondary air admitted to the air stream may be distributed across substantially the entire cross-sectional area thereof.

A still further object of the invention is to improve devices of the character described in sundry details hereinafter referred to and particularly pointed out in the appended claims.

Practical embodiments of the present invenmixed with the discharge.

uring Company, Racine,

Wisconsin ment indicated, as a tion are shown for illustrative purposes in the accompanying drawings, in which:

Fig. 1 is a vertical sectional elevational view of a unit heater embodying features ofthe present invention, and taken substantially as indicated by the line I-l of Fig. 2;

Fig. 2 is a bottom plan view of the structure illustrated in Fig. 1;

Fig. 3 is an enlarged fragmentary sectional elevational view of the deector retaining means illustrated in Figs. 1 and 2, and taken substantially as indicated by the line 3-3 of Fig. 2;

Fig. 4 is a fragmentary sectional elevational view of a unit heater similar to the one shown in Fig. 1 and illustrating a slightly modified 'arrangement of. the present invention with 'respect thereto;

Fig. 5 is an enlarged fragmentary sectional elevational view of the deflector retaining means embodied in the structure illustrated in Fig.4;

Fig. 6 is a plan sectional view of a slightly different type of unit' heater illustrating a further I,

embodimentof the thereto; and

Fig. '1 isy an enlarged perspective view of one of the deilectors illustrated in Fig.- 6.

It will be understood that in unit heater work, it is most desirable, if not necessary, to handle present invention applied a definite volume of air in relation to4 a definite v heat dissipation and, for the' reason that heated air rises, the discharge air temperatures must be kept down so that when the heated air is injected into the area to be heated, it will tend to mix properly instead of stratifying due to excessive temperature differentials.

In order to obtain a proper mixing of the heated air with the air of a room or other space to be heated, the present invention, as illustrated particularly in Figs. 1-to 3, inclusive, is shown in relation to a unit heaterof the type wherein the heated air is projected in a .downward direction and comprises a casing indicated, as a whole, by the numeral II, the said casing, in the present instance, comprising a main frame indicated, as a whole, by the numeral I2, having upper and lower plates I3 and I4. respectively, maintained in spaced relation with respect to each other by a plurality of spacers I5 in a manner to provide open side portions forming a primary 'air intake port I6 extending substantially around the frame.

Positioned in the port I6 between the edge portions of the plates I3 and I4 is a heating elewhole, by the numeral I1*- and shown, in the present instance, as comprising a plurality of fluid conducting coils I8 extending substantially around the outer side portion of the frame and having radiating fins I9 mounted thereon at the respective sides of the main frame I2, one end of the coils I8 being connected to a header communicating with a supply pipe 2I adapted to communicate through an opening 22 with. a suitable source of heating fluid, the opposite ends of the coils I8 being connected to a header 23 having a downwardly extending discharge end portion 24 for suitable disposal of the heating fluid passing through the coils I1.

As illustrated in Fig. 1 the plates I3 and I4 are provided, respectively, with aligned openings 25 and 26, and positioned in the opening 25 of the plate I3 is a truncated cone-shaped deflector 21 having a lower open end portion 28 in which is mounted, preferably on the upper side of the vde-A ector 21, a motor 29 having a shaft 3I extending below said cone-shaped member to the opposite side thereof and provided on its lower end with a fan 32 shown, in the present instance, as adapted to rotate'within the opening 26 formed -in the lower plate I4 of the main frame I2for,

impelling or drawing air through the heating element I1 and pas'tf'the coils I8 into the main frame and, by reason of the deilector 21, the heated air stream is directed in a downward direction, the motor 29 being adapted to be suitably connected to a source of electrical energy for rotating the fan 32.

Mounted, preferably on the lower plate I4, is

I a bracket indicated, as a whole, by the numeral relatively with respect to the member 35 and plate I4 of the main frame I2.

For suitably directing the air stream beyond the fan 32, a shroud 31 shown, in the present instance, as of substantially annular form having a discharge opening 38 at one side thereof is positioned below the plate I4, preferably in spaced relation thereto in a manner to provide an auxiliary or secondary air intake port 39 between the plate I4 and an adjacent portion of the shroud 31, through which secondary room-temperature air may be drawn into the air stream by Venturi action to mix therewith before being discharged into the space to be heated.

For further distributingor directing and mixing the air beyond the fan 32, a plurality of deflectors 40 are positioned within the shroud 31, and are shown, in the present instance, as extending radially from the hub portion 36, the deflectors 40, in the present instance, belngmounted adjacent one of their respective edge portions on rods 4I rotatably mounted adjacent their outer ends in the shroud 31, and at their inner ends in the hub portion 36, as clearly illustrated in Figs. l and 3. It will be apparent that the Venturi or secondary air drawn through the auxiliary intake port 39 will engage the delectors 4D and be directed laterally and inwardly thereby to mix with the primary or heated air stream as it is discharged from the device.

For retaining the defiectors 40 in various positions of adjustment, it will be noted, particularly by reference to Fig. 3, that the inner end portions of the rods 4I extend a substantial distance into lcn the hub portion 38, and that friction pads 42 positioned in the hub portion 36 are adapted to engage the respective opposite sides of the rods 4| adjacent the inner end portions thereof.

For exerting a binding action of the friction pads or members 42 on the adjacent portions of the rods 4l, a convex Washer 43 having a screwthreaded opening 44 formed therein is positioned within the hub portion 36 at one side of the friction pads 42, and at the opposite side thereof is .a concave washer 45 having an aperture 46 formed therein adapted to loosely receive a screwthreaded bolt 41 engaging the threaded opening 44 of the convex washer 43 for drawing the washers 43 and 45 snugly against the friction pads 42 in a manner to exert a binding action .on the sides of the inner end portions of the rods 4I, thereby providing a structure whereby the respective deflectors 40 secured to the respective rods 4I may be maintained-in various positions of adjustment with respect to the shroud 31 for directing the air as may be desired into the space to be heated.

It will be observed from the foregoing description that the present inventionprovides a novel construction and arrangement whereby heated air may be directed into a room, or the like, and wherein secondary or Venturi air of room temperature may be introduced through the secondary or auxiliary air intake port 39 into the air stream to mix therewith for lowering the temperature of the air stream in a manner to more readily mix with the air of the room and avoid stratifying of the air therein due to excessive temperature differentials of the heated air and that of the air within the space to be heated.

It will be observed also that by reason of the threaded relationship of the member 35 and hub portion 36, the hub portion, deflectors 40, and

-shroud 31 may be moved relatively with respect to the plate I4 in a manner to vary the opening of the secondary or auxiliary air intake port 39, and when this is determined, the parts may be retained in relatively ilxed position by means of "a set screw 48 (Fig. 3), furthermore, that the defiectors 40 may be readily adjusted at various angles with respect to the air stream for suitable distribution of the air, and retained in desired position by means of the friction pads 42, as clearly illustrated in Fig. 3.

Referring particularly to Figs. 4 and 5 of the drawings, the structure illustrated therein is substantially like that described with reference to Figs. l and 3, respectively, except that the shroud 31a is rigidlymounted on the plate I4a in fixed relation with respect thereto by means of spacers 5I in a manner to provide an auxiliary or secondary air inlet port 39a of fixed dimensions,

. the structure illustrated in Fig. 4 having a hub scribed with reference to Figs. l, 2, and 3 except that the auxiliary or secondary air intake portl V39a is fixed as to size and incapable of being varied as described-with reference to the structure illustrated in Figs. l, 2, and 3.

Referring to Figs. 6 and 7, the embodiment of the present invention illustrated therein is shown applied to a slightly diierent type of unit heater, wherein the heated air is directed, preferably, in a horizontal direction as distinguished from the downward direction of the structures illustrated in Figs. 1 to 5, inclusive, and in the arrangement shown in Fig. 6, the invention is applied to a unit heater comprising a casing indicated, as a Whole,

by the numeral I lb having a main frame I2b provided with an air intake port I6b and a motor 29b supported in said casing by means of rods 52, the motor shaft 3| b of the motor 2,91) being provided with a fan 32h for drawing air into the casing IIb through the air intake port I6b -of the frame [2b.

Mounted in the main frame 12b is a shroud 31h having a heating element indicated, as a whole, by the numeral Hb and comprising 4a plurality of heating coils I 8b mounted therein and a plurality of fins I9b mounted on said coils, the said shroud 31h being adapted to extend beyond the end of the main frame I2b opposite the air intake port |611 and provided with a discharge opening 38h adjacent one side of the shroud.

Mounted also in the shroud 31h adjacent the discharge opening 38h are a plurality of vertically spaced deflectors 40h shown, in the present instance, as arranged in series at opposite sides of a vertically disposed center post 53 and secured adjacent their rear edge portions to rods Hb pivotally mounted adjacent their inner end portions in the post 53 and at their outer end portions in the shroud 31h, each of the deflectors 40h being provided with spring ngers 5H having bosses 55 formed thereon adapted to engage a portion of the post 53 for retaining the deflectors 4Gb in various positions of adjustment with respect to the shroud.

As illustrated in Fig. '7, the deflectors 40h are of hollow construction comprising upper and lower wall portions 56 and 51, respectively. spaced from each other and having open outer end auxiliary or secondary air inlet portsmay be v aried as desired.

It will be observed also that by reason of the hollow character and open end and front edge portions of the deilectors 40h, the air passing between the deflectors will create a Venturi action adjacent the open front edge portions of the de-j flectors in a manner to draw room-temperature air from the secondary air intake ports 39h through the open end portions 58 of the deflectors into the hollow interior portion thereofin a manner to conduct the secondary or Venturi air of room temperature to adjacent the inner end portions of the defiectors and distribute the secondary or room-temperature air across substantially the entirecross sectional area of the air stream discharged from the unit heater, and that by reason of the adjustability of the deiiectors 40h, the air stream may be directed as desired into the space to be heated.

It will be observed from the foregoing description, that the present invention provides a novel construction and arrangement whereby auxiliary or secondary air of room temperature may be introduced into the heated-air stream of a unit heater for lowering the temperature thereof in a manner to condition the heated air for suitable co-mingling with the air of a room, or the like, to form a proper mixture therewith, and prevent stratifying of the air due to excessive temperature diiierentials, and` also, that the present invention provides novel .means whereby""'the amount or quantity of ksecondary air introduced Obviously, the present invention is not limited to the precise construction and arrangement shown and describedas the same may be variportions 58 and open longitudinal front edge portions 59. f

For admitting room-temperature air into the air stream passing through the shroud 31h, the shroud is provided adjacent the discharge side thereof and adjacent the outer open. end portions of the deflectors 40h with auxiliary or secondary air intake parte ash at the respective oppsite sides of the shroud, the secondary ports 3917 being shown, in the present instance, as provided with closure members 6I pivotally mounted at 52 whereby the size of the auxiliary or secondary air intake ports 39h may be varied.

It will be observed from the foregoing description that the primary air stream forced through the heating element and past the coils |8b and fins l9b, and thence through the discharge port 38h .of the shroud 31h will draw air of room temperature, by induced or Venturi action, through the secondary air intake ports 3917 into the space between the deflectors 40h to mix with the heated-air stream as it is discharged from Athe shroud and lower the temperature thereof in a manner to mix more readily with the air of theroom, and avoid stratifying of the air due to excessive temperature differentials of the heated heated, and that by reason of the adjustability of the closure members 6l, the size or area ofthe ously modified. Moreover, all the features of the invention need not be used conjointly as the same may be used to advantage in variously different air and that of the air within the space to be combinations and sub-combinations.

What I claim as new. and desire to secure by Letters Patent is:

port. said casing having an auxiliary airport for admitting relatively cool secondary air by induction into the primary air stream after it has passed said heating element, and a plurality of defiectors adjacent said discharge port, for intermixing the air from said primary and secondary air streams.

2. A unit heater comprising a casing having an air intake port and a discharge port, a heating element in said casing,. means for impelling air through said element and discharge port, said casing having an auxiliary air port communicating with the air stream between said intake and discharge ports for inducing additional air into said air stream, and a plurality of deflectors adjacent said discharge port, for intermixing the induced air withV said air stream;

3. A unit heater comprising a main frame having an air intake port formed therein, a, shroud having a discharge port at one side thereof mounted cn said frame, a heating element in said frame, means for impelling air through said elehaving a discharge port at one side thereof mounted on said frame, a heating element in said frame, means for impelling air through said element, shroud and discharge port, a portion of said shroud being spaced from said frame to provide an auxiliary air port communicating directly with the air stream passing between said intake and discharge ports, and a plurality oi' deectors adjustably mounted in said shroud, for intermixing air from said auxiliary port with said air stream.

5. A unit heater comprising a main frame having an air intake port formed therein, a shroud having a discharge port at one side thereof mounted on said frame, a heating element in said frame, means for impelling air through said element, shroud, and,.discharge port, a portion of said shroud being spaced from said frame to provide an auxiliary air port communicating with the air. stream passing between said impelling means and the discharge port, said auxiliary port admitting relatively cool induced air into said air stream, a plurality of adjustable deectors pivotally mounted in said shroud for intermixing said induced air with said air stream, andmeans operatively related to said shroud for retaining the deiiectors in various positions of adjustment with respect thereto.

6. A unit heater comprising a main frame having an air intake port formed therein, a shroud having a discharge port at one side thereof mounted on said frame, a heating element in said frame, means for impelling air through said element, shroud and discharge port, said shroud being spaced from said frame to provide an auxiliary air port 'communicating directly with the air stream passing between said intake and discharge ports, a plurality of radially disposed deflectors pivotally mounted in said shroud for intermixing` air from said auxiliary port with said air stream and direct said mixed air stream from 'the heater, and means within said shroud and operatively related to said deflectors for retaining the deilectors in various positions of adjustment with respect thereto. '1. A unit heater comprising a main frame having an air intake port formed therein, an annular shroud having a discharge port at one side thereof mounted on said frame, a heating element in said frame, means for impelling air through said element, shroud, and discharge port, said shroud being spaced from said frame to provide an auxiliary air port communicating with the air stream passing between said intake and discharge ports for admitting relatively cool air into said air stream, a plurality of radially disposed defiectors pivotally mounted in said shroud, and means adjacent the inner ends of said deilectors and operatively related to the pivots thereof for retaining the deflectors in various angular positions of adjustment `with respect to said shroud.

8. A unit heater comprising a main frame having an air intake port formed therein, a shroud having a discharge port at one side 'thereof mounted on said frame, a heating element in said frame, means for impelling air through said element, 4shroud and discharge port, said shroud being spaced from said frame to provide an auxiliary air port `communicating with the air stream passing between said intake and discharge ports for admitting air into said stream, and means operatively related to said shroud and frame for varying the size of said auxiliary air port.

9. zA unit heater comprising a main frame having an air intake port formed therein, a shroud having a discharge port at one side thereof mounted on said frame in spaced relation thereto to provide an auxiliary air port between said intake and discharge ports, a, heating element positioned in said inlet port, means for impelling air through said element, past said auxiliary port and through said discharge port, a hub portion Within said shroud, a plurality of radially disposed adjustable deflectors having pivot rods rotatably mounted in said shroud and hub portion, and means mounted on said hub portion and operatively related to said rods for securing the deilectors in relatively xed position with respect to said shroud.

10. A unit heater comprising a main frame having an air intake port formed therein, an annular shroud having a discharge port at one side thereof mounted on and relatively movable with respect to said frame, said shroud being spaced with respect to said frame to provide an auxiliary air port between said intake and discharge ports, a heating element positioned in said inlet port, means for impelling air through said element, past said auxiliary air port and through said discharge port, a hub portion within said shroud, a plurality of radially disposed adjustable deflectors having pivot rods secured thereto and rotatably mounted in said shroud and hub portion, and

friction means mounted in said hub portionop eratively related to said rods for securing the deflectors in relatively fixed positions of adjustment with respect to said shroud.

11. A unit heater comprisingl a main frame having an air intake port formed therein, an

annular shroud having a discharge port at one side thereof mounted on and relatively movable with respect to said frame, said shroud being spaced with respect to said frame to provide an annular auxiliary ai1` port between said intake and discharge ports, a heating element positioned in said inlet port, means for impelling air through said element, past said auxiliary air port, and through said discharge port, a hub portion within said shroud adjacent the central portion thereof, a plurality of radially disposed adjustable deilectors having pivot rods secured thereto and rotatably mounted in said shroud and hub portion, manually operated friction means mounted in said hub portion and operatively related to said rods for securing the. defiectors in relatively fixed positions of adjustment with respect to said shroud, and means for moving said hub portion, deectors and shroud relatively to said frame.

12. A unit heater comprising a main frame having an article port formed therein, a bracket mounted on said frame and having a screw threaded member adjacent its central portion, a screw threaded hub portion operatively related to said member and rotatable thereon for moving the hub with respect to said frame, a pluralplurality of deilectors secured, respectively, to

said rods, an. annular shroud surrounding said deectors and mounted on opposite ends of said rods, and manually operated friction means in said hub operatively related to said rods for securing said deiiectors in relatively fixed positions with respect to said shroud.

13. A unit heater comprising a main frame having an air intakeport formed therein adjacent the sides thereof, a bracket member mounted on said frameV and having a screw threaded member adjacent its central portion, a screw threaded hub portion operatively related to said member and rotatable thereon for moving the hub with respect to said frame, a plurality of radially disposed rods rotatably mounted adjacent their inner ends in said hub portion, a plurality of deiiectors secured, respectively, to said rods, an annular shroud having a discharge port at one side thereof surrounding said deflectors mounted on the outer ends of said rods in spaced relation to said frame to provide an auxiliary air port between said intake and discharge ports,

spective central portions, spaced heating coils extending around said frame between the edge portions of said plates to provide a hollow'portion .within said frame, a truncated cone-shaped deector mounted on said upper plate and extending through the opening therein into the hollow portion of said frame, a motor mounted on said deflector and having a shaft extending downwardly to the opposite side thereof, a fan on said shaft positioned in the opening of said lower plate, a bracket comprising radially disposed bars having their outer end portions mounted on said lower plate and having a screw threaded member secured to the inner end portions of said bars, a screw threaded hub portion operatively related to said member and rotatable thereon for moving said hub longitudinally of said member and with respect to said bars and lower plate, a plurality of radially disposed rodsrotatably mounted adjacent their inner ends in said hub portion, a plurality of defiecto'rs secured, respectively, to said rods, an annular shroud having a discharge port at one side thereof surrounding said defiectors mounted on the outer ends of said rods in spaced relation to said frame to provide an auxiliary air port between said intake and discharge ports, and manually operated friction means in said hub operatively 'related to opposite sides of said rods for adjust-'- ably securing said deectors in various positions of adjustment with respect to said shroud.

15. A deector mounting comprising a shroud, a hollow hub portion, a plurality of radially disposed rods rotatably mounted in said shroud and hub portion, deiiectors secured to said rods, friction means in said hub portion, and manually operated means for urging said friction means into engagement with said rods for securing the deflectors in variousl positions of adjustment with respect to said shroud and hub portion.

16. A deector mounting comprising a shroud, a hollow hub portion, a plurality of radially disposed rods rotatably mounted in Said shroud an'd hub portion, deiiectors secured to said rods, friction washers in said hub portion at opposite sides of said rods, pressure plates at opposite Sides of l spaced relation with respect thereto to provide an auxiliary air port between said intake and discharge ports, a heating element positioned in said inlet port, means for impelling air through said element, past said auxiliary port, and through said discharge iprt, a hollow hub portion within said shroud,'ia plurality of radially disposed adjustable deiiectors having pivot rods rotatably mounted in said shroud and hub portion, the inner end portions of said rods extending a substantial distance into said hub and means in said hub portion and operatively related to the inner end portions of said rods for securing the deilectors in relatively fixed position with respect to said shroud.

18. A unit heater comprising a main frame having an air intake port formed therein adjacent the sides thereof, an annular shroud having a discharge port at one side thereof rigidly mounted on said frame in iixedspaced relation with respect thereto to provide an annular auxiliary air port between said intake and discharge ports,-

a heating element positioned in said inlet port, means for impelling air through said element, past said auxiliary port and through said discharge port, a hollow hub portion within said shroud adjacent the central portion thereof, a plurality of radially disposed adjustable deflectors within said shroud and having pivot rods rotatably mounted in said shroud and hub portion, the inner end portions of saidy rods extending a substantial distance into said hub, a pair of friction washers mounted in said hub portion and operatively related, respectively, to the opposite sides of the inner end portions of said rods, and manually operated means for drawing said washers against the inner end portions of said rods forl securing the deflectors in various xed positions of adjustment with respect to said shroud.

19. A unit heater comprising a main frame having an air intake port formed therein, a shroud having a discharge port at one side thereof mounted in said frame, a heating element in said frame, and means for impelling air through said element, shroud and discharge port, said shroud having an auxiliary air port adjacent said discharge port for admitting room-temperature". kair to the iheated air stream as the latter is discharged from said unit heater.

20. A unit heater comprising a main frame having an air intake port formed therein, a shroud having a discharge port at one side thereof mounted in said frame, a heating element in said frame, means for impelling air through said element, shroud and discharge port, said shroud having auxiliary air ports adjacent the respective opposite sides of said discharge port for admitting room-temperature air to the heated air stream as the latter is discharged from said unit heater.

213A unit heater comprising a main frame having an air intake port formed therein, a shroud having a discharge port at one side thereof mounted in said frame, a heating element mounted in saidframe, a heating element in said shroud, a plurality of hollow deilectors adjustabLv mounted adjacent said discharge port, said deiiectors having open outer end portions, means for impelling air through said element, shroud and discharge port and between said deflectors, said shroud having auxiliaryair ports adjacent `the respective outer ends of said deflectors for admitting room-temperature air into and between said deilectors and into the heated air stream after .the latter has passed through said heating element.

23. A unit heater comprising a main frame having an air intake port formed therein, a

shroud having a discharge port at one side thereof mounted in said frame, a heating element in said shroud, a plurality of adjustable hollow defiectors pivotally mounted adjacent said discharge port, said deiiectors having open outer end and front edge portions, means for impeiling air through said element, shroud and discharge port and between said deectors, said shroud having auxiliary air ports adjacent the respective outer ends of said hollow deilectors for admitting roomtemperature air into and between said deiiectors and into the heated air stream after the latter has passed through said heating element, and means ior varying the size of said auxiliary air ports.

24. A diiusion grille adapted to be disposed transversely of a stream of primary air, comprising a plurality of laterally spaced conduit-like vanes between which said air flows, means mounting said vanes for turning about their longitudinal axes to change the direction of flow of air issuing from the grille, at least some of the vanesl being provided on their lee sides with aspirating openings and having inlet openings at theirends for the entrance of secondary air, whereby said secondary air is drawn out of said aspirating openings by said primary air and mixed therewith.

RICHARD C. JEPER'IINGER. 

